1. Field of the Invention
The present invention relates in general to document reading and printing using optical solid-state scanners, and more particularly, to a small optical scan head for use in a document reading and recording apparatus.
2. Description of the Prior Art
Typical prior art optical scan heads comprise a housing with discrete simultaneously energized light emitting diode (LED) set therein, and further include a complicated fiber bundle light transmission channel for spreading out the light emitted from these LEDs and applying the light to a surface such as, for example, a document face. A plurality of photodetectors is also set in the housing for detecting light reflected from a prescribed area of the document face.
Discrete fiber optic bundles are generally utilized in the prior art to transmit reflected light from a designated section of the document area to a photodetector allotted for that designated section. Since each section in the area being scanned by the scan head has a corresponding photodetector, there must be a one-to-one correspondence between that particular section, its discrete fiber optic bundle, and the respective photodetector for that particular section. Because these light emitting diodes are energized simultaneously and the light emitted therefrom is spread out over the area being scanned, it is critical to maintain the precise alignment of each photodetector with its attendant fiber optic bundle. Otherwise, light from one section of the area being scanned might be detected both by the respective photodetector for that particular section and by an adjacent photodetector. Such detection by an adjacent photodetector would clearly cause an erroneous reading from the document face.
The above-described scan assembly system may be characterized as a spatially-dependent system. In other words, each particular segment of an area is blocked off and a particular photodetector is designated therefor. This type of prior art scan assembly system is particularly ill-suited for applications with small volume or packaging constraint. This is so because of the criticality of the fiber optic bundle photodetector alignment noted above. Additionally, this type of system has a relatively high power consumption.